MAGNETRON ROTATING DIRECT-CURRENT ARC USING GRAPHITE-FURNACE SAMPLE INTRODUCTION FOR MICROSOLUTION ANALYSIS

A direct current (dc) arc plasma in Ar or He at atmospheric pressure is formed between the tip of a W/Th wire cathode and the end of a coaxial graphite tube anode. A magnetic field parallel to the electrode axis is used to generate a motorlike rotation of the arc current channel at frequencies in the 2–3 kHz range. This results in a diffuse current sheet covering the end of the anode tube. Sample vapor from a graphite tube furnace is introduced into the arc plasma by passing the vapor through the anode tube. This ensures adequate sample-plasma interaction and results in detection limits generally in the parts per billion range. Design features of the arc-furnace system are presented along with analytical data for the elements Cu, Mn, Mg, Cr, Zn, Cd, and Fe. The results of the experiments using Ar and Ar/He mixtures as the arc plasma gas are compared. © 1990, American Chemical Society. All rights reserved.